Dancing Lady
What kind of sorcery is this?! This is known as the silhouette illusion; it’s a kinetic, and bi-stable optical illusion that resembles a twirling female dancer. It was originally distributed as a GIF animation, created in 2003 by Japanese web designer Nobuyuki Kayahara. Some people initially see the figure as spinning clockwise, but others see it as counterclockwise.
Source: yousense.info
The direction of the turn is still disputed to this day, so I guess it’s up to you to decide! To get technical, the illusion comes from the lack of visual cues for depth. Like as the dancer’s arms move from your left to right, it’s possible to see her arms passing between the body and the viewer.